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Patel KP, Katsurada K, Zheng H. Cardiorenal Syndrome: The Role of Neural Connections Between the Heart and the Kidneys. Circ Res 2022; 130:1601-1617. [PMID: 35549375 PMCID: PMC9179008 DOI: 10.1161/circresaha.122.319989] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The maintenance of cardiovascular homeostasis is highly dependent on tightly controlled interactions between the heart and the kidneys. Therefore, it is not surprising that a dysfunction in one organ affects the other. This interlinking relationship is aptly demonstrated in the cardiorenal syndrome. The characteristics of the cardiorenal syndrome state include alterations in neurohumoral drive, autonomic reflexes, and fluid balance. The evidence suggests that several factors contribute to these alterations. These may include peripheral and central nervous system abnormalities. However, accumulating evidence from animals with experimental models of congestive heart failure and renal dysfunction as well as humans with the cardiorenal syndrome suggests that alterations in neural pathways, from and to the kidneys and the heart, including the central nervous system are involved in regulating sympathetic outflow and may be critically important in the alterations in neurohumoral drive, autonomic reflexes, and fluid balance commonly observed in the cardiorenal syndrome. This review focuses on studies implicating neural pathways, particularly the afferent and efferent signals from the heart and the kidneys integrating at the level of the paraventricular nucleus in the hypothalamus to alter neurohumoral drive, autonomic pathways, and fluid balance. Further, it explores the potential mechanisms of action for the known beneficial use of various medications or potential novel therapeutic manipulations for the treatment of the cardiorenal syndrome. A comprehensive understanding of these mechanisms will enhance our ability to treat cardiorenal conditions and their cardiovascular complications more efficaciously and thoroughly.
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Affiliation(s)
- Kaushik P Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (K.P.P.)
| | - Kenichi Katsurada
- Division of Cardiovascular Medicine, Department of Internal Medicine (K.K.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi, Japan.,Division of Clinical Pharmacology, Department of Pharmacology (K.K.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi, Japan
| | - Hong Zheng
- Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion (H.Z.)
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Honetschlagerová Z, Gawrys O, Jíchová Š, Škaroupková P, Kikerlová S, Vaňourková Z, Husková Z, Melenovský V, Kompanowska-Jezierska E, Sadowski J, Kolář F, Novotný J, Hejnová L, Kujal P, Červenka L. Renal Sympathetic Denervation Attenuates Congestive Heart Failure in Angiotensin II-Dependent Hypertension: Studies with Ren-2 Transgenic Hypertensive Rats with Aortocaval Fistula. Kidney Blood Press Res 2021; 46:95-113. [PMID: 33530085 DOI: 10.1159/000513071] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 11/14/2020] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE We examined if renal denervation (RDN) attenuates the progression of aortocaval fistula (ACF)-induced heart failure or improves renal hemodynamics in Ren-2 transgenic rats (TGR), a model of angiotensin II (ANG II)-dependent hypertension. METHODS Bilateral RDN was performed 1 week after creation of ACF. The animals studied were ACF TGR and sham-operated controls, and both groups were subjected to RDN or sham denervation. In separate groups, renal artery blood flow (RBF) responses were determined to intrarenal ANG II (2 and 8 ng), norepinephrine (NE) (20 and 40 ng) and acetylcholine (Ach) (10 and 40 ng) 3 weeks after ACF creation. RESULTS In nondenervated ACF TGR, the final survival rate was 10 versus 50% in RDN rats. RBF was significantly lower in ACF TGR than in sham-operated TGR (6.2 ± 0.3 vs. 9.7 ± 0.5 mL min-1 g-1, p < 0.05), the levels unaffected by RDN. Both doses of ANG II decreased RBF more in ACF TGR than in sham-operated TGR (-19 ± 3 vs. -9 ± 2% and -47 ± 3 vs. -22 ± 2%, p < 0.05 in both cases). RDN did not alter RBF responses to the lower dose, but increased it to the higher dose of ANG II in sham-operated as well as in ACF TGR. NE comparably decreased RBF in ACF TGR and sham-operated TGR, and RDN increased RBF responsiveness. Intrarenal Ach increased RBF significantly more in ACF TGR than in sham-operated TGR (29 ± 3 vs. 17 ± 3%, p < 0.05), the changes unaffected by RDN. ACF creation induced marked bilateral cardiac hypertrophy and lung congestion, both attenuated by RDN. In sham-operated but not in ACF TGR, RDN significantly decreased mean arterial pressure. CONCLUSION The results show that RDN significantly improved survival rate in ACF TGR; however, this beneficial effect was not associated with improvement of reduced RBF or with attenuation of exaggerated renal vascular responsiveness to ANG II.
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Affiliation(s)
- Zuzana Honetschlagerová
- Center for Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czechia,
| | - Olga Gawrys
- Center for Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czechia.,Department of Cardiology, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Šárka Jíchová
- Center for Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Petra Škaroupková
- Center for Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Soňa Kikerlová
- Center for Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Zdeňka Vaňourková
- Center for Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Zuzana Husková
- Center for Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Vojtěch Melenovský
- Department of Cardiology, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Elzbieta Kompanowska-Jezierska
- Department of Renal and Body Fluid Physiology, Mossakowski Medical Research Centre, Polish Academy of Science, Warsaw, Poland
| | - Janusz Sadowski
- Department of Renal and Body Fluid Physiology, Mossakowski Medical Research Centre, Polish Academy of Science, Warsaw, Poland
| | - František Kolář
- Department of Developmental Cardiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czechia
| | - Jiří Novotný
- Department of Physiology, Faculty of Science, Charles University in Prague, Prague, Czechia
| | - Lucie Hejnová
- Department of Physiology, Faculty of Science, Charles University in Prague, Prague, Czechia
| | - Petr Kujal
- Center for Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czechia.,Department of Pathology, 3rd Faculty of Medicine, Charles University, Prague, Czechia
| | - Luděk Červenka
- Center for Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czechia
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Nalos L, Švíglerová J, Rajdl D, Jedlička J, Dejmek J, Štengl M, Kuncová J. Norepinephrine turnover in the left ventricle of subtotally nephrectomized rats. Physiol Res 2019; 68:S233-S242. [PMID: 31928041 DOI: 10.33549/physiolres.934354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Increased activity of the sympathetic nervous system (SNS) has been proposed as a risk factor for increased cardiovascular mortality in patients with chronic kidney disease (CKD). Information on the activity of cardiac sympathetic innervation is non-homogeneous and incomplete. The aim of our study was to evaluate the tonic effect of SNS on heart rate, norepinephrine turnover and direct and indirect effects of norepinephrine in left ventricles of subtotally nephrectomized rats (SNX) in comparison with sham-operated animals (SHAM). Renal failure was verified by measuring serum creatinine and urea levels. SNX rats developed increased heart rates and blood pressure (BP). The increase in heart rate was not caused by sympathetic overactivity as the negative chronotropic effect of metipranolol did not differ between the SNX and SHAM animals. The positive inotropic effects of norepinephrine and tyramine on papillary muscle were not significantly different. Norepinephrine turnover was measured after the administration of tyrosine hydroxylase inhibitor, pargyline, tyramine, desipramine, and KCl induced depolarization. The absolute amount of released norepinephrine was comparable in both groups despite a significantly decreased norepinephrine concentration in the cardiac tissue of the SNX rats. We conclude that CKD associated with renal denervation in rats led to adaptive changes characterized by an increased reuptake and intracellular norepinephrine turnover which maintained normal reactivity of the heart to sympathetic stimulation.
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Affiliation(s)
- L Nalos
- Institute of Physiology, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic.
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Zheng H, Liu X, Katsurada K, Patel KP. Renal denervation improves sodium excretion in rats with chronic heart failure: effects on expression of renal ENaC and AQP2. Am J Physiol Heart Circ Physiol 2019; 317:H958-H968. [PMID: 31490733 DOI: 10.1152/ajpheart.00299.2019] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Previously we have shown that increased expression of renal epithelial sodium channels (ENaC) may contribute to the renal sodium and water retention observed during chronic heart failure (CHF). The goal of this study was to examine whether renal denervation (RDN) changed the expressions of renal sodium transporters ENaC, sodium-hydrogen exchanger-3 proteins (NHE3), and water channel aquaporin 2 (AQP2) in rats with CHF. CHF was produced by left coronary artery ligation in rats. Four weeks after ligation surgery, surgical bilateral RDN was performed. The expression of ENaC, NHE3, and AQP2 in both renal cortex and medulla were measured. As a functional test for ENaC activation, diuretic and natriuretic responses to ENaC inhibitor benzamil were monitored in four groups of rats (Sham, Sham+RDN, CHF, CHF+RDN). Western blot analysis indicated that RDN (1 wk later) significantly reduced protein levels of α-ENaC, β-ENaC, γ-ENaC, and AQP2 in the renal cortex of CHF rats. RDN had no significant effects on the protein expression of kidney NHE3 in both Sham and CHF rats. Immunofluorescence studies of kidney sections confirmed the reduced signaling of ENaC and AQP2 in the CHF+RDN rats compared with the CHF rats. There were increases in diuretic and natriuretic responses to ENaC inhibitor benzamil in rats with CHF. RDN reduced the diuretic and natriuretic responses to benzamil in CHF rats. These findings suggest a critical role for renal nerves in the enhanced expression of ENaC and AQP2 and subsequent pathophysiology of renal sodium and water retention associated with CHF.NEW & NOTEWORTHY This is the first study to show in a comprehensive way that renal denervation initiated after a period of chronic heart failure reduces the expression of epithelial sodium channels and aquaporin 2 leading to reduced epithelial sodium channel function and sodium retention.
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Affiliation(s)
- Hong Zheng
- Division of Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, Vermillion, South Dakota
| | - Xuefei Liu
- Division of Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, Vermillion, South Dakota
| | - Kenichi Katsurada
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Kaushik P Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
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Zheng H, Katsurada K, Liu X, Knuepfer MM, Patel KP. Specific Afferent Renal Denervation Prevents Reduction in Neuronal Nitric Oxide Synthase Within the Paraventricular Nucleus in Rats With Chronic Heart Failure. Hypertension 2019; 72:667-675. [PMID: 30012866 DOI: 10.1161/hypertensionaha.118.11071] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Renal denervation (RDN) has been shown to restore endogenous neuronal nitric oxide synthase (nNOS) in the paraventricular nucleus (PVN) and reduce sympathetic drive during chronic heart failure (CHF). The purpose of the present study was to assess the contribution of afferent renal nerves to the nNOS-mediated sympathetic outflow within the PVN in rats with CHF. CHF was induced in rats by ligation of the left coronary artery. Four weeks after surgery, selective afferent RDN (A-RDN) was performed by bilateral perivascular application of capsaicin on the renal arteries. Seven days after intervention, nNOS protein expression, nNOS immunostaining signaling, and diaphorase-positive stained cells were significantly decreased in the PVN of CHF rats, changes that were reversed by A-RDN. A-RDN reduced basal lumbar sympathetic nerve activity in rats with CHF (8.5%±0.5% versus 17.0%±1.2% of max). Microinjection of nNOS inhibitor L-NMMA (L-NG-monomethyl arginine citrate) into the PVN produced a blunted increase in lumbar sympathetic nerve activity in rats with CHF. This response was significantly improved after A-RDN (Δ lumbar sympathetic nerve activity: 25.7%±2.4% versus 11.2%±0.9%). Resting afferent renal nerves activity was substantially increased in CHF compared with sham rats (56.3%±2.4% versus 33.0%±4.7%). These results suggest that intact afferent renal nerves contribute to the reduction of nNOS in the PVN. A-RDN restores nNOS and thus attenuates the sympathoexcitation. Also, resting afferent renal nerves activity is elevated in CHF rats, which may highlight a crucial neural mechanism arising from the kidney in the maintenance of enhanced sympathetic drive in CHF.
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Affiliation(s)
- Hong Zheng
- From the Division of Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, Vermillion (H.Z., X.L.)
| | - Kenichi Katsurada
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (K.K., K.P.P.)
| | - Xuefei Liu
- From the Division of Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, Vermillion (H.Z., X.L.)
| | - Mark M Knuepfer
- Department of Pharmacology and Physiology, St. Louis University School of Medicine, MO (M.M.K.)
| | - Kaushik P Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (K.K., K.P.P.)
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Ichige MHA, Pereira MG, Brum PC, Michelini LC. Experimental Evidences Supporting the Benefits of Exercise Training in Heart Failure. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 999:181-206. [PMID: 29022264 DOI: 10.1007/978-981-10-4307-9_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Heart Failure (HF), a common end point for many cardiovascular diseases, is a syndrome with a very poor prognosis. Although clinical trials in HF have achieved important outcomes in reducing mortality, little is known about functional mechanisms conditioning health improvement in HF patients. In parallel with clinical studies, basic science has been providing important discoveries to understand the mechanisms underlying the pathophysiology of HF, as well as to identify potential targets for the treatment of this syndrome. In spite of being the end-point of cardiovascular derangements caused by different etiologies, autonomic dysfunction, sympathetic hyperactivity, oxidative stress, inflammation and hormonal activation are common factors involved in the progression of this syndrome. Together these causal factors create a closed link between three important organs: brain, heart and the skeletal muscle. In the past few years, we and other groups have studied the beneficial effects of aerobic exercise training as a safe therapy to avoid the progression of HF. As summarized in this chapter, exercise training, a non-pharmacological tool without side effects, corrects most of the HF-induced neurohormonal and local dysfunctions within the brain, heart and skeletal muscles. These adaptive responses reverse oxidative stress, reduce inflammation, ameliorate neurohormonal control and improve both cardiovascular and skeletal muscle function, thus increasing the quality of life and reducing patients' morbimortality.
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Affiliation(s)
- Marcelo H A Ichige
- Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Marcelo G Pereira
- Department of Biodynamics of Human Body Movement, School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil
| | - Patrícia C Brum
- Department of Biodynamics of Human Body Movement, School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil. .,National Institute for Science & Technology - INCT (In)activity & Exercise, CNPq - Niterói (RJ), Rio de Janeiro, Brazil.
| | - Lisete C Michelini
- Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.,National Institute for Science & Technology - INCT (In)activity & Exercise, CNPq - Niterói (RJ), Rio de Janeiro, Brazil
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7
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Mahata SK, Zheng H, Mahata S, Liu X, Patel KP. Effect of heart failure on catecholamine granule morphology and storage in chromaffin cells. J Endocrinol 2016; 230:309-23. [PMID: 27402067 PMCID: PMC4980258 DOI: 10.1530/joe-16-0146] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 06/24/2016] [Indexed: 12/16/2022]
Abstract
One of the key mechanisms involved in sympathoexcitation in chronic heart failure (HF) is the activation of the adrenal glands. Impact of the elevated catecholamines on the hemodynamic parameters has been previously demonstrated. However, studies linking the structural effects of such overactivation with secretory performance and cell metabolism in the adrenomedullary chromaffin cells in vivo have not been previously reported. In this study, HF was induced in male Sprague-Dawley rats by ligation of the left coronary artery. Five weeks after surgery, cardiac function was assessed by ventricular hemodynamics. HF rats showed increased adrenal weight and adrenal catecholamine levels (norepinephrine, epinephrine and dopamine) compared with sham-operated rats. Rats with HF demonstrated increased small synaptic and dense core vesicle in splanchnic-adrenal synapses indicating trans-synaptic activation of catecholamine biosynthetic enzymes, increased endoplasmic reticulum and Golgi lumen width to meet the demand of increased catecholamine synthesis and release, and more mitochondria with dilated cristae and glycogen to accommodate for the increased energy demand for the increased biogenesis and exocytosis of catecholamines from the adrenal medulla. These findings suggest that increased trans-synaptic activation of the chromaffin cells within the adrenal medulla may lead to increased catecholamines in the circulation which in turn contributes to the enhanced neurohumoral drive, providing a unique mechanistic insight for enhanced catecholamine levels in plasma commonly observed in chronic HF condition.
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Affiliation(s)
- Sushil K Mahata
- VA San Diego Healthcare System Metabolic Physiology & Ultrastructural Biology Lab.Department of Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Hong Zheng
- Department of Cellular and Integrative PhysiologyUniversity of Nebraska Medical Center, Omaha, NE, USA
| | - Sumana Mahata
- Caltech Division of BiologyCalifornia Institute of Technology, Pasadena, CA, USA
| | - Xuefei Liu
- Department of Cellular and Integrative PhysiologyUniversity of Nebraska Medical Center, Omaha, NE, USA
| | - Kaushik P Patel
- Department of Cellular and Integrative PhysiologyUniversity of Nebraska Medical Center, Omaha, NE, USA
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Patel KP, Xu B, Liu X, Sharma NM, Zheng H. Renal Denervation Improves Exaggerated Sympathoexcitation in Rats With Heart Failure: A Role for Neuronal Nitric Oxide Synthase in the Paraventricular Nucleus. Hypertension 2016; 68:175-84. [PMID: 27185748 DOI: 10.1161/hypertensionaha.115.06794] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 04/15/2016] [Indexed: 01/05/2023]
Abstract
Renal denervation (RDN) has been postulated to reduce sympathetic drive during heart failure (HF), but the central mechanisms are not completely understood. The purpose of the present study was to assess the contribution of neuronal nitric oxide synthase (nNOS) within the paraventricular nucleus (PVN) in modulating sympathetic outflow in rats with HF that underwent RDN. HF was induced in rats by ligation of the left coronary artery. Four weeks after surgery, bilateral RDN was performed. Rats with HF had an increase in FosB-positive cells in the PVN with a concomitant increase in urinary excretion of norepinephrine, and both of these parameters were ameliorated after RDN. nNOS-positive cells immunostaining, diaphorase staining, and nNOS protein expression were significantly decreased in the PVN of HF rats, findings that were ameliorated by RDN. Microinjection of nNOS inhibitor N(G)-monomethyl l-arginine into the PVN resulted in a blunted increase in lumbar sympathetic nerve activity (11±2% versus 24±2%) in HF than in sham group. This response was normalized after RDN. Stimulation of afferent renal nerves produced a greater activation of PVN neurons in rats with HF. Afferent renal nerve stimulation elicited a greater increase in lumbar sympathetic nerve activity in rats with HF than in sham rats (45±5% versus 22±2%). These results suggest that intact renal nerves contribute to the reduction of nNOS in the PVN, resulting in the activation of the neurons in the PVN of rats with HF. RDN restores nNOS and thus attenuates the sympathoexcitation commonly observed in HF.
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Affiliation(s)
- Kaushik P Patel
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha.
| | - Bo Xu
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha
| | - Xuefei Liu
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha
| | - Neeru M Sharma
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha
| | - Hong Zheng
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha
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Miller DB, Snow SJ, Schladweiler MC, Richards JE, Ghio AJ, Ledbetter AD, Kodavanti UP. Acute Ozone-Induced Pulmonary and Systemic Metabolic Effects Are Diminished in Adrenalectomized Rats. Toxicol Sci 2016; 150:312-22. [PMID: 26732886 DOI: 10.1093/toxsci/kfv331] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Acute ozone exposure increases circulating stress hormones and induces metabolic alterations in animals. We hypothesized that the increase of adrenal-derived stress hormones is necessary for both ozone-induced metabolic effects and lung injury. Male Wistar-Kyoto rats underwent bilateral adrenal demedullation (DEMED), total bilateral adrenalectomy (ADREX), or sham surgery (SHAM). After a 4 day recovery, rats were exposed to air or ozone (1 ppm), 4 h/day for 1 or 2 days and responses assessed immediately postexposure. Circulating adrenaline levels dropped to nearly zero in DEMED and ADREX rats relative to SHAM. Corticosterone tended to be low in DEMED rats and dropped to nearly zero in ADREX rats. Adrenalectomy in air-exposed rats caused modest changes in metabolites and lung toxicity parameters. Ozone-induced hyperglycemia and glucose intolerance were markedly attenuated in DEMED rats with nearly complete reversal in ADREX rats. Ozone increased circulating epinephrine and corticosterone in SHAM but not in DEMED or ADREX rats. Free fatty acids (P = .15) and branched-chain amino acids increased after ozone exposure in SHAM but not in DEMED or ADREX rats. Lung minute volume was not affected by surgery or ozone but ozone-induced labored breathing was less pronounced in ADREX rats. Ozone-induced increases in lung protein leakage and neutrophilic inflammation were markedly reduced in DEMED and ADREX rats (ADREX > DEMED). Ozone-mediated decreases in circulating white blood cells in SHAM were not observed in DEMED and ADREX rats. We demonstrate that ozone-induced peripheral metabolic effects and lung injury/inflammation are mediated through adrenal-derived stress hormones likely via the activation of stress response pathway.
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Affiliation(s)
- Desinia B Miller
- *Curriculum in Toxicology, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina 27599; and
| | - Samantha J Snow
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
| | - Mette C Schladweiler
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
| | - Judy E Richards
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
| | - Andrew J Ghio
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
| | - Allen D Ledbetter
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
| | - Urmila P Kodavanti
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
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Zheng H, Liu X, Sharma NM, Li Y, Pliquett RU, Patel KP. Urinary Proteolytic Activation of Renal Epithelial Na+ Channels in Chronic Heart Failure. Hypertension 2015; 67:197-205. [PMID: 26628676 DOI: 10.1161/hypertensionaha.115.05838] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 10/30/2015] [Indexed: 12/31/2022]
Abstract
One of the key mechanisms involved in renal Na(+) retention in chronic heart failure (CHF) is activation of epithelial Na(+) channels (ENaC) in collecting tubules. Proteolytic cleavage has an important role in activating ENaC. We hypothesized that enhanced levels of proteases in renal tubular fluid activate ENaC, resulting in renal Na(+) retention in rats with CHF. CHF was produced by left coronary artery ligation in rats. By immunoblotting, we found that several urinary serine proteases were significantly increased in CHF rats compared with sham rats (fold increases: furin 6.7, prostasin 23.6, plasminogen 2.06, and plasmin 3.57 versus sham). Similar increases were observed in urinary samples from patients with CHF. Whole-cell patch clamp was conducted in cultured renal collecting duct M-1 cells to record Na(+) currents. Protease-rich urine (from rats and patients with CHF) significantly increased the Na(+) inward current in M-1 cells. Two weeks of protease inhibitor treatment significantly abrogated the enhanced diuretic and natriuretic responses to ENaC inhibitor benzamil in rats with CHF. Increased podocyte lesions were observed in the kidneys of rats with CHF by transmission electron microscopy. Consistent with these results, podocyte damage markers desmin and podocin expressions were also increased in rats with CHF (increased ≈2-folds). These findings suggest that podocyte damage may lead to increased proteases in the tubular fluid, which in turn contributes to the enhanced renal ENaC activity, providing a novel mechanistic insight for Na(+) retention commonly observed in CHF.
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Affiliation(s)
- Hong Zheng
- From the Department of Cellular and Integrative Physiology (H.Z., X.L., N.M.S., K.P.P.) and Department of Emergency Medicine (Y.L.), University of Nebraska Medical Center, Omaha; and Department of Internal Medicine II, University Hospital Halle, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany (R.U.P.)
| | - Xuefei Liu
- From the Department of Cellular and Integrative Physiology (H.Z., X.L., N.M.S., K.P.P.) and Department of Emergency Medicine (Y.L.), University of Nebraska Medical Center, Omaha; and Department of Internal Medicine II, University Hospital Halle, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany (R.U.P.)
| | - Neeru M Sharma
- From the Department of Cellular and Integrative Physiology (H.Z., X.L., N.M.S., K.P.P.) and Department of Emergency Medicine (Y.L.), University of Nebraska Medical Center, Omaha; and Department of Internal Medicine II, University Hospital Halle, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany (R.U.P.)
| | - Yulong Li
- From the Department of Cellular and Integrative Physiology (H.Z., X.L., N.M.S., K.P.P.) and Department of Emergency Medicine (Y.L.), University of Nebraska Medical Center, Omaha; and Department of Internal Medicine II, University Hospital Halle, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany (R.U.P.)
| | - Rainer U Pliquett
- From the Department of Cellular and Integrative Physiology (H.Z., X.L., N.M.S., K.P.P.) and Department of Emergency Medicine (Y.L.), University of Nebraska Medical Center, Omaha; and Department of Internal Medicine II, University Hospital Halle, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany (R.U.P.)
| | - Kaushik P Patel
- From the Department of Cellular and Integrative Physiology (H.Z., X.L., N.M.S., K.P.P.) and Department of Emergency Medicine (Y.L.), University of Nebraska Medical Center, Omaha; and Department of Internal Medicine II, University Hospital Halle, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany (R.U.P.).
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11
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Shin MK, Han W, Bevans-Fonti S, Jun JC, Punjabi NM, Polotsky VY. The effect of adrenal medullectomy on metabolic responses to chronic intermittent hypoxia. Respir Physiol Neurobiol 2014; 203:60-7. [PMID: 25179887 DOI: 10.1016/j.resp.2014.08.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 08/22/2014] [Accepted: 08/24/2014] [Indexed: 01/14/2023]
Abstract
Obstructive sleep apnea causes intermittent hypoxia (IH) and is associated with insulin resistance and type 2 diabetes. IH increases plasma catecholamine levels, which may increase insulin resistance and suppress insulin secretion. The objective of this study was to determine if adrenal medullectomy (MED) prevents metabolic dysfunction in IH. MED or sham surgery was performed in 60 male C57BL/6J mice, which were then exposed to IH or control conditions (intermittent air) for 6 weeks. IH increased plasma epinephrine and norepinephrine levels, increased fasting blood glucose and lowered basal and glucose-stimulated insulin secretion. MED decreased baseline epinephrine and prevented the IH induced increase in epinephrine, whereas the norepinephrine response remained intact. MED improved glucose tolerance in mice exposed to IH, attenuated the impairment in basal and glucose-stimulated insulin secretion, but did not prevent IH-induced fasting hyperglycemia or insulin resistance. We conclude that the epinephrine release from the adrenal medulla during IH suppresses insulin secretion causing hyperglycemia.
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Affiliation(s)
- Mi-Kyung Shin
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, United States
| | - Woobum Han
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, United States
| | - Shannon Bevans-Fonti
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, United States
| | - Jonathan C Jun
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, United States
| | - Naresh M Punjabi
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, United States
| | - Vsevolod Y Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, United States.
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12
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Holdsworth CT, Copp SW, Hirai DM, Ferguson SK, Sims GE, Hageman KS, Stebbins CL, Poole DC, Musch TI. The effects of dietary fish oil on exercising skeletal muscle vascular and metabolic control in chronic heart failure rats. Appl Physiol Nutr Metab 2013; 39:299-307. [PMID: 24552370 DOI: 10.1139/apnm-2013-0301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Impaired vasomotor control in chronic heart failure (CHF) is due partly to decrements in nitric oxide synthase (NOS) mediated vasodilation. Exercising muscle blood flow (BF) is augmented with polyunsaturated fatty acid (PUFA) supplementation via fish oil (FO) in healthy rats. We hypothesized that FO would augment exercising muscle BF in CHF rats via increased NO-bioavailability. Myocardial infarction (coronary artery ligation) induced CHF in Sprague-Dawley rats which were subsequently randomized to dietary FO (20% docosahexaenoic acid, 30% eicosapentaenoic acid, n = 15) or safflower oil (SO, 5%, n = 10) for 6-8 weeks. Mean arterial pressure (MAP), blood [lactate], and hindlimb muscles BF (radiolabeled microspheres) were determined at rest, during treadmill exercise (20 m·min(-1), 5% incline) and exercise + N(G)-nitro-l-arginine-methyl-ester (l-NAME) (a nonspecific NOS inhibitor). FO did not change left ventricular end-diastolic pressure (SO: 14 ± 2; FO: 11 ± 1 mm Hg, p > 0.05). During exercise, MAP (SO: 128 ± 3; FO: 132 ± 3 mm Hg) and blood [lactate] (SO: 3.8 ± 0.4; FO: 4.6 ± 0.5 mmol·L(-1)) were not different (p > 0.05). Exercising hindlimb muscle BF was lower in FO than SO (SO: 120 ± 11; FO: 93 ± 4 mL·min(-1)·100 g(-1), p < 0.05) but was not differentially affected by l-NAME. Specifically, 17 of 28 individual muscle BF's were lower (p < 0.05) in FO demonstrating that PUFA supplementation with FO in CHF rats does not augment muscle BF during exercise but may lower metabolic cost.
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Affiliation(s)
- Clark T Holdsworth
- a Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506-5802, USA
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13
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Abstract
The temporal relationship between the development of heart failure and activation of the neurohumoral systems involved in chronic heart failure (CHF) has not been precisely defined. When a compensatory mechanism switches to a deleterious contributing factor in the progression of the disease is unclear. This article addresses these issues through evaluating the contribution of various cardiovascular reflexes and cellular mechanisms to the sympathoexcitation in CHF. It also sheds light on some of the important central mechanisms that contribute to the increase in sympathetic nerve activity in CHF.
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Affiliation(s)
- Irving H Zucker
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, 985850 Nebraska Medical Center, Omaha, NE 68198-5850, USA.
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14
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Patel KP, Zheng H. Central neural control of sympathetic nerve activity in heart failure following exercise training. Am J Physiol Heart Circ Physiol 2011; 302:H527-37. [PMID: 22101524 DOI: 10.1152/ajpheart.00676.2011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Typical characteristics of chronic congestive heart failure (HF) are increased sympathetic drive, altered autonomic reflexes, and altered body fluid regulation. These abnormalities lead to an increased risk of mortality, particularly in the late stage of chronic HF. Recent evidence suggests that central nervous system (CNS) mechanisms may be important in these abnormalities during HF. Exercise training (ExT) has emerged as a nonpharmacological therapeutic strategy substitute with significant benefit to patients with HF. Regular ExT improves functional capacity as well as quality of life and perhaps prognosis in chronic HF patients. The mechanism(s) by which ExT improves the clinical status of HF patients is not fully known. Recent studies have provided convincing evidence that ExT significantly alleviates the increased sympathetic drive, altered autonomic reflexes, and altered body fluid regulation in HF. This review describes and highlights the studies that examine various central pathways involved in autonomic outflow that are altered in HF and are improved following ExT. The increased sympathoexcitation is due to an imbalance between inhibitory and excitatory mechanisms within specific areas in the CNS such as the paraventricular nucleus (PVN) of the hypothalamus. Studies summarized here have revealed that ExT improves the altered inhibitory pathway utilizing nitric oxide and GABA mechanisms within the PVN in HF. ExT alleviates elevated sympathetic outflow in HF through normalization of excitatory glutamatergic and angiotensinergic mechanisms within the PVN. ExT also improves volume reflex function and thus fluid balance in HF. Preliminary observations also suggest that ExT induces structural neuroplasticity in the brain of rats with HF. We conclude that improvement of the enhanced CNS-mediated increase in sympathetic outflow, specifically to the kidneys related to fluid balance, contributes to the beneficial effects of ExT in HF.
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Affiliation(s)
- Kaushik P Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA.
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15
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Zheng H, Liu X, Li Y, Sharma NM, Patel KP. Gene transfer of neuronal nitric oxide synthase to the paraventricular nucleus reduces the enhanced glutamatergic tone in rats with chronic heart failure. Hypertension 2011; 58:966-73. [PMID: 21968757 DOI: 10.1161/hypertensionaha.111.176222] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Our previous studies have shown that the decreased NO and increased glutamatergic mechanisms on sympathetic regulation within the paraventricular nucleus (PVN) may contribute to the elevated sympathoexcitation during chronic heart failure (CHF). In the present study, we investigated the effects of neuronal NO synthase (nNOS) gene transfer on N-methyl-D-aspartic acid receptor subunit NR(1) in the rats with a coronary ligation model of CHF. Adenovirus vectors encoding nNOS (AdnNOS) or adenovirus vectors encoding β-galactosidase were transfected into the PVN in vivo. Five days after application of AdnNOS, the increased expression of nNOS within the PVN was confirmed by NADPH-diaphorase staining, real-time PCR, and Western blot. In anesthetized rats, AdnNOS treatment significantly enhanced the blunted renal sympathetic nerve activity, blood pressure, and heart rate responses to NO synthase inhibitor N(G)-monomethyl-L-arginine in the rats with CHF compared with CHF-adenovirus vectors encoding β-galactosidase group. AdnNOS significantly decreased the enhanced renal sympathetic nerve activity, blood pressure, and heart rate responses to N-methyl-D-aspartic acid in the rats with CHF (renal sympathetic nerve activity: 44±2% versus 79±6%; P<0.05) compared with CHF-adenovirus vectors encoding the β-galactosidase group. AdnNOS transfection significantly reduced the increased NR(1) receptor mRNA expression (Δ35±5%) and protein levels (Δ24±4%) within the PVN in CHF rats. Furthermore, in neuronal NG-108 cells, NR(1) receptor protein expression decreased in a dose-dependent manner after AdnNOS transfection. According to our results, nNOS downregulation enhances glutamate transmission in the PVN by increasing NR(1) subunit expression. This mechanism may enhance renal sympathetic nerve activity in CHF rats.
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Affiliation(s)
- Hong Zheng
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, 985850 Nebraska Medical Center, Omaha, NE 68198-5850, USA
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16
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Affiliation(s)
- Marcelo D Carattino
- Renal-Electrolyte Division, Department of Medicine and Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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17
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Zheng H, Liu X, Rao US, Patel KP. Increased renal ENaC subunits and sodium retention in rats with chronic heart failure. Am J Physiol Renal Physiol 2010; 300:F641-9. [PMID: 21159737 DOI: 10.1152/ajprenal.00254.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Renal tubular dysfunction could be involved in the increased sodium and water reabsorption in chronic heart failure (CHF). The goal of the present study was to examine the molecular basis for the increased renal sodium and water retention in CHF. We hypothesized that dysregulation of renal epithelial sodium channels (ENaC) could be involved in the pathogenesis of CHF. The left coronary ligation-induced model of heart failure in the rat was used. Real-time PCR and Western blot analysis indicated that the mRNA and protein abundance of α-, β-, and γ-subunits of ENaC were significantly increased by in the cortex (mRNA: α-ENaC Δ104 ± 24%, β-ENaC Δ47 ± 16%, γ-ENaC Δ55 ± 18%; protein: α-ENaC Δ114 ± 28%, β-ENaC Δ150 ± 31%, γ-ENaC Δ39 ± 5% compared with sham rats) and outer medulla (mRNA: α-ENaC Δ52 ± 18%, β-ENaC Δ38 ± 8%, γ-ENaC Δ39 ± 13%; protein: α-ENaC Δ88 ± 16%, β-ENaC Δ94 ± 28%, γ-ENaC Δ45 ± 9% compared with sham rats) of CHF compared with sham-operated rats. Immunohistochemistry microscopy confirmed the increased labeling of α-, β-, and γ-ENaC subunits in the collecting duct segments in rats with CHF. Furthermore, there was a significant increase in diuretic (7-fold compared with sham) and natriuretic responses (3-fold compared with sham) to ENaC inhibitor benzamil in the rats with CHF. Absence of renal nerves produced a greater contribution of ENaC in sodium retention in rats with CHF. These results suggest that the increased expression of renal ENaC subunits may contribute to the renal sodium and water retention observed during CHF.
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Affiliation(s)
- Hong Zheng
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA.
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18
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Prognosis in patients with congestive heart failure and subacute renal failure treated with hemodialysis. Wien Klin Wochenschr 2009; 121:391-7. [DOI: 10.1007/s00508-009-1158-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2009] [Indexed: 10/20/2022]
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19
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Kleiber AC, Zheng H, Schultz HD, Peuler JD, Patel KP. Exercise training normalizes enhanced glutamate-mediated sympathetic activation from the PVN in heart failure. Am J Physiol Regul Integr Comp Physiol 2008; 294:R1863-72. [PMID: 18385465 DOI: 10.1152/ajpregu.00757.2007] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exercise training (ExT) normalizes the increased sympathetic outflow in heart failure (HF), but the mechanisms are not known. We hypothesized that ExT would normalize the augmented glutamatergic mechanisms mediated by N-methyl-d-aspartic acid (NMDA) receptors within the paraventricular nucleus (PVN) that occur with HF. Four groups of rats were used: 1) sham-operated (Sham) sedentary (Sed), 2) Sham ExT, 3) HF Sed, and 4) HF ExT. HF was induced by left coronary artery ligation, and ExT consisted of 3 wk of treadmill running. In alpha-chloralose-urethane-anesthetized rats, the increase in renal sympathetic nerve activity in response to the highest dose of NMDA (200 pmol) injected into the PVN in the HF Sed group was approximately twice that of the Sham Sed group. In the HF ExT group the response was not different from the Sham Sed and Sham ExT groups. Relative NMDA NR1 receptor subunit mRNA expression was 63% higher in the HF Sed group compared with the Sham Sed group but in the HF ExT group was not different from the Sham Sed and Sham ExT groups. NR1 receptor subunit protein expression was increased 87% in the HF Sed group compared with the Sham Sed group but in the HF ExT group was not significantly different from the Sham Sed and Sham ExT groups. Thus one mechanism by which ExT alleviates elevated sympathetic outflow in HF may be through normalization of glutamatergic mechanisms within the PVN.
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Affiliation(s)
- Allison C Kleiber
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, 985850 Nebraska Medical Center, Omaha, NE 68198-5850, USA
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20
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Novotny M, Quaiserova-Mocko V, Wehrwein EA, Kreulen DL, Swain GM. Determination of endogenous norepinephrine levels in different chambers of the rat heart by capillary electrophoresis coupled with amperometric detection. J Neurosci Methods 2007; 163:52-9. [PMID: 17383009 PMCID: PMC2679869 DOI: 10.1016/j.jneumeth.2007.02.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2006] [Revised: 02/12/2007] [Accepted: 02/12/2007] [Indexed: 12/27/2022]
Abstract
Capillary electrophoresis with end-column amperometric detection (CE-EC) was used to determine the regional distribution of norepinephrine (NE) in the hearts of sympathetically innervated (control) and chemically sympathectomized rats. Key features of the method are (i) the sample preparation and clean-up step that involved the application of off-line solid phase extraction (SPE) with a 95% NE recovery and (ii) the use of a diamond microelectrode for detection. NE was quantified in the left and right ventricle, the ventricular septum, and the left and right atrium. The NE concentration in the atria was three to five times higher than in the ventricles and ventricular septum of control rats. Basal NE levels in the left and right ventricle and the ventricular septum were reduced to below the detection limit (0.034 microg/g tissue) in tissues treated with the neurotoxin, 6-hydroxydopamine (6-OHDA), while only a moderate reduction was observed in the left and right atrium. Importantly, the diamond microelectrode provided low and stable background current and low peak-to-peak noise <or=0.65 pA at a detection potential of +0.86 V versus Ag/AgCl. A reproducible electrode response was observed for multiple injections of tissue homogenates with minimal response attenuation due to electrode fouling.
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Affiliation(s)
- Martin Novotny
- Department of Chemistry and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
| | - Veronika Quaiserova-Mocko
- Department of Chemistry and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
| | - Erica A. Wehrwein
- Department of Physiology and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
| | - David L. Kreulen
- Department of Physiology and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
- Corresponding authors: Greg M. Swain, Department of Chemistry, Michigan State University, 320 Chemistry Building, East Lansing, MI 48824-1322. Tel. (517) 355-9715 x229, Fax. (517)353-1793, Email. . David L. Kreulen, Department of Physiology, Michigan State University, 2201 Biomedical Physical Sciences Building, East Lansing, MI 48824-1320. Tel. (517) 355-6475 x1312, Fax. (517) 355-5125, Email.
| | - Greg M. Swain
- Department of Chemistry and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
- Corresponding authors: Greg M. Swain, Department of Chemistry, Michigan State University, 320 Chemistry Building, East Lansing, MI 48824-1322. Tel. (517) 355-9715 x229, Fax. (517)353-1793, Email. . David L. Kreulen, Department of Physiology, Michigan State University, 2201 Biomedical Physical Sciences Building, East Lansing, MI 48824-1320. Tel. (517) 355-6475 x1312, Fax. (517) 355-5125, Email.
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21
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Zheng H, Li YF, Zucker IH, Patel KP. Exercise training improves renal excretory responses to acute volume expansion in rats with heart failure. Am J Physiol Renal Physiol 2006; 291:F1148-56. [PMID: 16822936 DOI: 10.1152/ajprenal.00501.2005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Experiments were performed to test the postulate that exercise training (ExT) improves the blunted renal excretory response to acute volume expansion (VE), in part, by normalizing the neural component of the volume reflex typically observed in chronic heart failure (HF). Diuretic and natriuretic responses to acute VE were examined in sedentary and ExT groups of rats with either HF or sham-operated controls. Experiments were performed in anesthetized (Inactin) rats 6 wk after coronary ligation surgery. Histological data indicated that there was a 34.9 +/- 3.0% outer and 42.5 +/- 3.2% inner infarct of the myocardium in the HF group. Sham rats had no observable damage to the myocardium. In sedentary rats with HF, VE produced a blunted diuresis (46% of sham) and natriuresis (35% of sham) compared with sham-operated control rats. However, acute VE-induced diuresis and natriuresis in ExT rats with HF were comparable to sham rats and significantly higher than sedentary HF rats. Renal denervation abolished the salutary effects of ExT on renal excretory response to acute VE in HF. Since glomerular filtration rates were not significantly different between the groups, renal hemodynamic changes may not account for the blunted renal responses in rats with HF. Additional experiments confirmed that renal sympathetic nerve activity responses to acute VE were blunted in sedentary HF rats; however, ExT normalized the renal sympathoinhibition in HF rats. These results confirm an impairment of neurally mediated excretory responses to acute VE in rats with HF. ExT restored the blunted excretory responses as well as the renal sympathoinhibitory response to acute VE in HF rats. Thus the beneficial effects of ExT on cardiovascular regulation in HF may be partly due to improvement of the neural component of volume reflex.
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Affiliation(s)
- Hong Zheng
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, 985850 Nebraska Medical Center, Omaha, NE 68198-5850, USA
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22
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Trautner S, Amtorp O, Boesgaard S, Andersen CB, Galbo H, Haunsoe S, Sheykhzade M. Noradrenaline-induced increases in calcium and tension in skeletal muscle conductance and resistance arteries from rats with post-infarction heart failure. Eur J Pharmacol 2006; 537:143-54. [PMID: 16626691 DOI: 10.1016/j.ejphar.2006.03.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 02/07/2006] [Accepted: 03/13/2006] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that arterial reactivity to noradrenaline is augmented in congestive heart failure (CHF), which could contribute to the deleterious changes in peripheral vascular resistance and compliance in this condition. From male Wistar rats with post-infarction CHF and sham-operated rats, skeletal muscle conductance and resistance arteries (mean lumen diameters: 514 and 186 microm) were isolated and mounted on wire myographs, and wall tension was recorded in response to cumulative application of acetylcholine and noradrenaline to the vessel segments. In a subset of experiments, wall tension and cytosolic free calcium ion concentration [Ca(2+)](i) were recorded simultaneously during noradrenaline application, using wire myography and the FURA-2 technique. No significant differences were found in the arterial baseline levels of [Ca(2+)](i) or tension between CHF and sham rats. In the resistance arteries of CHF rats, the noradrenaline-induced increases in [Ca(2+)](i) were significantly enhanced (P=0.003). Despite the augmented [Ca(2+)](i) levels, the tension responses to noradrenaline were unaltered in these arteries. In the conductance arteries, there were no significant differences in noradrenaline-induced [Ca(2+)](i) or tension responses between CHF and control rats. CHF did not alter vascular morphology or change vascular relaxations to acetylcholine in either type of artery. In conclusion, these results do not support the contention that arterial reactivity to noradrenaline is augmented in the skeletal muscle vascular bed in CHF. On the contrary, the unchanged contractile responsiveness in the resistance arteries despite the enhanced levels of [Ca(2+)](i) during noradrenaline application suggests that the contractile function of these vessels is compromised in CHF. Neither vascular remodeling, endothelial dysfunction nor changes in baseline vascular tone could be demonstrated in the skeletal muscle vascular bed of this animal model of heart failure.
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Affiliation(s)
- Simon Trautner
- Department of Cardiology, The Danish National Hospital, Rigshospitalet, Blegdamsvej 9, Copenhagen, DK-2100, Denmark
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23
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Abstract
A number of neurohumoral processes are activated in heart failure, including an increase in the plasma concentration of norepinephrine. Few studies have been performed to examine the role of the central nervous system in the activation of sympathetic outflow during heart failure (HF). In this paper I review these limited studies, with particular emphasis on examining the role of the paraventricular nucleus (PVN) in the exaggerated sympathetic outflow commonly observed in heart failure. The conclusion is that heart failure is associated with changes in specific areas in the brain and that alterations in the activation of neurons in the PVN are likely related to abnormalities in vasopressin production, blood volume regulation, and sympathoexcitation observed in the heart failure state. Furthermore, neuronal nitric oxide within the PVN that is involved in mediating sympathetic outflow via a GABA mechanism from the PVN may be deficient in inhibiting overall sympathetic outflow leading to the exaggerated sympathetic outflow commonly observed in heart failure.
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Affiliation(s)
- K P Patel
- Department of Physiology and Biophysics, University of Nebraska Medical Center, Omaha, Nebraska, 68198-4575, USA
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24
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Kennedy SL, Nickerson M, Campisi J, Johnson JD, Smith TP, Sharkey C, Fleshner M. Splenic norepinephrine depletion following acute stress suppresses in vivo antibody response. J Neuroimmunol 2005; 165:150-60. [PMID: 15978673 DOI: 10.1016/j.jneuroim.2005.05.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Accepted: 05/06/2005] [Indexed: 11/25/2022]
Abstract
Exposure to an intense acute stressor immediately following immunization leads to a reduction in anti-KLH IgM, IgG, and IgG2a, but not IgG1. Stress also depletes splenic norepinephrine (NE) content. Immunization during pharmacological (alpha-methyl-p-tyrosine) or stress-induced splenic NE depletion results in antibody suppression similar to that found in rats immunized prior to stressor exposure. Prevention of splenic NE depletion during stress by tyrosine, but not pharmacological elevation (mirtazapine) of NE, resulted in normal antibody responses. These data support the hypothesis that splenic NE depletion is necessary and sufficient for stress-induced suppression of antibody to a T-cell dependent antigen.
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Affiliation(s)
- S L Kennedy
- Department of Integrative Physiology, University of Colorado, Campus Box 354, Boulder, Colorado 80309-0354, USA
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25
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Burniston JG, Tan LB, Goldspink DF. β2-Adrenergic receptor stimulation in vivo induces apoptosis in the rat heart and soleus muscle. J Appl Physiol (1985) 2005; 98:1379-86. [PMID: 15591297 DOI: 10.1152/japplphysiol.00642.2004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
High doses of the β2-adrenergic receptor (AR) agonist clenbuterol can induce necrotic myocyte death in the heart and slow-twitch skeletal muscle of the rat. However, it is not known whether this agent can also induce myocyte apoptosis and whether this would occur at a lower dose than previously reported for myocyte necrosis. Male Wistar rats were given single subcutaneous injections of clenbuterol. Immunohistochemistry was used to detect myocyte-specific apoptosis (detected on cryosections via a caspase 3 antibody and confirmed with annexin V, single-strand DNA labeling, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling). Myocyte apoptosis was first detected at 2 h and peaked 4 h after clenbuterol administration. The lowest dose of clenbuterol to induce cardiomyocyte apoptosis was 1 μg/kg, with peak apoptosis (0.35 ± 0.05%; P < 0.05) occurring in response to 5 mg/kg. In the soleus, peak apoptosis (5.8 ± 2%; P < 0.05) was induced by the lower dose of 10 μg/kg. Cardiomyocyte apoptosis was detected throughout the ventricles, atria, and papillary muscles. However, this damage was most abundant in the left ventricular subendocardium at a point 1.6 mm, that is, approximately one-quarter of the way, from the apex toward the base. β-AR antagonism (involving propranolol, bisoprolol, or ICI 118551) or reserpine was used to show that clenbuterol-induced myocardial apoptosis was mediated through neuromodulation of the sympathetic system and the cardiomyocyte β1-AR, whereas in the soleus direct stimulation of the myocyte β2-AR was involved. These data show that, when administered in vivo, β2-AR stimulation by clenbuterol is detrimental to cardiac and skeletal muscles even at low doses, by inducing apoptosis through β1- and β2-AR, respectively.
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MESH Headings
- Adrenergic beta-2 Receptor Agonists
- Adrenergic beta-Agonists/administration & dosage
- Animals
- Apoptosis/drug effects
- Apoptosis/physiology
- Clenbuterol/administration & dosage
- Dose-Response Relationship, Drug
- Heart/drug effects
- Male
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/cytology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Myocardium/cytology
- Myocardium/metabolism
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Rats
- Rats, Wistar
- Receptors, Adrenergic, beta-2/metabolism
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Affiliation(s)
- Jatin G Burniston
- Research Institute for Sports and Exercise Sciences, Liverpool John Moores Univ., Webster St., Liverpool, L3 2ET, United Kingdom.
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26
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Abstract
Hypertension is present in the majority of patients with chronic renal failure and constitutes a major risk factor for the very high cardiovascular morbidity and mortality in this patient population. Furthermore hypertension is known to be a substantial progression factor in renal disease. In the past, it had been presumed that hypertension in chronic renal failure is due to enhanced sodium retention, chronic hypervolemia and increased activity of the renin-angiotensin-aldosterone-system. Recent studies now provide evidence that sympathetic overactivity plays an additional important role and also promotes progression of renal failure. The treatment goal in renal patients is to delay or even prevent progression of renal failure and to reduce the cardiovascular risk. Recent studies have investigated the respective impact of sympatholytic drugs, e.g. inhibitors of the renin-angiotensin-aldosterone-system, beta-blockers or I1-Imidazolin-receptor-agonists in fulfilling these aims. The present report will review experimental and clinical studies on the role of sympathetic overactivity in hypertension and chronic renal failure and possible new therapeutic options.
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Affiliation(s)
- Antje Habicht
- Klinische Abteilung für Nephrologie und Dialyse, Universitätsklinik für Innere Medizin III, Wien, Osterreich
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Hong Y, Hui SSC, Chan BTY, Hou J. Effect of berberine on catecholamine levels in rats with experimental cardiac hypertrophy. Life Sci 2003; 72:2499-507. [PMID: 12650858 DOI: 10.1016/s0024-3205(03)00144-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The aim of this study is to investigate the effect of berberine on catecholamine level (adrenaline and noradrenaline) in rats with experimental cardiac hypertrophy. Cardiac hypertrophy(CH) was induced by suprarenal abdominal aorta constriction, and the drugs were administered for 8 weeks starting from 4 weeks after surgery. The degree of cardiac hypertrophy was determined by heart and left ventricular weight. The level of adrenaline(AD) and noradrenaline(NA) was detected by HPLC. The data showed that in the CH model rats, the level of plasma and left ventricular tissue AD, and the level of NA in plasma were higher than that of the age-matched controls(indicating increased "total" sympathetic activity). The level of NA in left ventricular tissue of CH model rats was however lower than the age-matched controls. Berberine and captopril showed significant effect on inhibiting the development of cardiac hypertrophy. Berberine decreased plasma NA level and the AD level both in plasma and left ventricular tissue, but had no effect on improving the cardiac NA depletion. Captopril showed significant effect on increasing the depleted cardiac NA and in reducing the elevated plasma NA level. These findings show the efficacy of berberine on modulating the sympathetic nervous activity of rats with experimental cardiac hypertrophy, and reflect the therapeutic potentials of berberine in patients with cardiac hypertrophy and chronic heart failure.
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Affiliation(s)
- Ying Hong
- Division of Chinese Medicine, School of Professional and Continuing Education, The University of Hong Kong, 1/F Austin Tower, 22-26A Austin Avenue, Tsim Sha Tsui, Kowloon, Hong Kong, China.
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Weiss ML, Kenney MJ, Musch TI, Patel KP. Modifications to central neural circuitry during heart failure. ACTA PHYSIOLOGICA SCANDINAVICA 2003; 177:57-67. [PMID: 12492779 DOI: 10.1046/j.1365-201x.2003.01047.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIM During heart failure (HF), excess sodium retention is triggered by increased plasma renin-angiotensin-aldosterone activity and increased basal sympathetic nerve discharge (SND). Enhanced basal SND in the renal nerves plays a role in sodium retention. Therefore, as a hypothetical model for the central sympathetic control pathways that are dysregulated as a consequence of HF, the central neural pathways regulating the sympathetic motor output to the kidney are reviewed in the context of their role during HF. CONCLUSION From these findings, a model of the neuroanatomical circuitry that may be affected during HF is constructed.
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Affiliation(s)
- M L Weiss
- Department of Anatomy and Physiology, Kansas State University, 1600 Denison Avenue, Manhattan, KS 66506-5602, USA
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Kopp UC, Cicha MZ, Smith LA. Impaired responsiveness of renal mechanosensory nerves in heart failure: role of endogenous angiotensin. Am J Physiol Regul Integr Comp Physiol 2003; 284:R116-24. [PMID: 12388453 DOI: 10.1152/ajpregu.00336.2002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Increasing renal pelvic pressure results in PGE(2)-mediated release of substance P. Substance P increases afferent renal nerve activity (ARNA), which leads to a reflex increase in urinary sodium excretion (U(Na)V). Endogenous ANG II modulates the responsiveness of renal mechanosensory nerves. The ARNA and U(Na)V responses are suppressed by low- and enhanced by high-sodium diet. We examined whether the ARNA responses are altered in rats with congestive heart failure (CHF), a condition characterized by increased ANG II and sodium retention. The ARNA responses to increasing renal pelvic pressure </=7.5 mmHg were suppressed in CHF vs. sham-CHF rats fed normal sodium diet. In CHF rats, increasing renal pelvic pressure 2.5 and 7.5 mmHg increased ARNA 0 +/- 1 and 13 +/- 2% (P < 0.01) before and 9 +/- 1 (P < 0.01) and 19 +/- 1% (P < 0.01) during renal pelvic perfusion with losartan. Losartan had no effect on the ARNA responses in sham-CHF rats. In isolated renal pelvises from CHF rats, PGE(2) increased substance P release from 11 +/- 2 to 15 +/- 3 pg/min (not significant) without and from 16 +/- 2 to 30 +/- 4 pg/min (P < 0.01) with losartan in the incubation bath. Losartan had no effect on PGE(2)-mediated substance P release in sham-CHF rats. In conclusion, the responsiveness of renal mechanosensory nerves is impaired in CHF rats due to ANG II inhibiting PGE(2)-mediated release of substance P from renal pelvic nerves.
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Affiliation(s)
- Ulla C Kopp
- Department of Internal Medicine, Department of Veterans Affairs Medical Center, and University of Iowa Roy J. and Lucille Carver College of Medicine, Iowa City, Iowa 52242, USA.
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Arabia AM, Catapano L, Storini C, Perego C, De Luigi A, Head GA, De Simoni MG. Impaired central stress-induced release of noradrenaline in rats with heart failure: a microdialysis study. Neuroscience 2002; 114:591-9. [PMID: 12220562 DOI: 10.1016/s0306-4522(02)00337-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Sympathetic hyperactivity in rats with heart failure is associated with increased extracellular noradrenaline in the hypothalamic paraventricular nucleus at rest. However, it is unknown how this nucleus responds to stressful stimuli. In the present study we therefore examined the basal and stress-induced release of noradrenaline in the paraventricular nucleus of conscious Sprague-Dawley rats with heart failure measured by in vivo microdialysis. Basal noradrenaline concentration in the paraventricular nucleus of rats with heart failure was more than double that in sham-operated controls. Immobilization stress decreases noradrenaline levels in the paraventricular nucleus of rats with heart failure to 57% of baseline, while it increased in sham-operated controls to 228%. However, serum corticosterone was similarly elevated at 30 and 90 min post-stress in both experimental groups. We have shown that heart failure causes an impairment of the central noradrenergic system's response to acute sympatho-excitation but does not affect the hypothalamo-pituitary-adrenocortical response.
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Affiliation(s)
- A M Arabia
- Inflammation and Nervous System Disease Laboratory, Istituto di Ricerche Farmacologiche Mario Negri, Milan 20157, Italy.
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Lohmeier TE. Neurohumoral regulation of arterial pressure in hemorrhage and heart failure. Am J Physiol Regul Integr Comp Physiol 2002; 283:R810-4. [PMID: 12228048 DOI: 10.1152/ajpregu.00414.2002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Thomas E Lohmeier
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi 39216-4505, USA.
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Yang Z, Zhang T, Coote JH. Synchrony analysis between blood pressure and sympathetic nerve signal inhibited by atrial receptor stimulation in Wistar rats. Exp Physiol 2002; 87:461-8. [PMID: 12392110 DOI: 10.1111/j.1469-445x.2002.tb00059.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recently attempts have been made to analyse blood pressure (BP) and renal sympathetic nerve activity (RSNA) to determine how patterns contained within them might reflect control by the autonomic nervous system. To date, these studies have primarily used coherence analysis of BP and RSNA in the frequency domain. However, this analysis is unable to assess the non-linear properties of the underlying cardiovascular control system. In this study we employed not only coherence analysis but also cross-entropy analysis using balloon inflation ('balloon-on') to assess the influence of right atrial receptors on the relationship between BP and RSNA under two conditions in anaesthetised Wistar rats. Balloon-on stimulation alone inhibited RSNA by 28 +/- 4% in eight rats without changing BP. This effect on integrated nerve activity was not present when atrial stimulation was applied during stimulation of a site in the paraventricular nucleus (PVN) of the hypothalamus which increased RSNA by 158.7 +/- 58% and increased BP by 17.1 +/- 2.3 mmHg. However, the cross-entropy measurement was significantly decreased (P < 0.05) during balloon-on stimulation in both the conditions revealing that there is greater synchrony between the oscillating signals contained within the BP and RSNA time series. Thus during the enhanced RSNA elicited by stimulation of the PVN, the inhibitory influence of atrial receptors, although apparently blocked, was still effective in that it resulted in the energy of the RSNA spectrum becoming more evenly distributed over a range of frequencies. The data show that cross-entropy calculations are able to characterize the non-linearities of underlying cardiovascular control.
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Affiliation(s)
- Zhuo Yang
- Division of Medical Sciences-Physiology, School of Medicine, University of Birmingham, UK
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Zhang K, Li YF, Patel KP. Reduced endogenous GABA-mediated inhibition in the PVN on renal nerve discharge in rats with heart failure. Am J Physiol Regul Integr Comp Physiol 2002; 282:R1006-15. [PMID: 11893604 DOI: 10.1152/ajpregu.00241.2001] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
One characteristic of heart failure (HF) is increased sympathetic activation. The paraventricular nucleus (PVN) of the hypothalamus (involved in control of sympathetic outflow) has been shown to have increased neuronal activation during HF. This study examined the influence of endogenous GABA input (inhibitory in nature) into the PVN on renal sympathetic nerve discharge (RSND), arterial blood pressure (BP), and heart rate (HR) in rats with HF induced by coronary artery ligation. In alpha-chloralose- and urethane-anesthetized rats, microinjection of bicuculline (a GABA antagonist) into the PVN produced a dose-dependent increase in RSND, BP, and HR in both sham-operated control and HF rats. Bicuculline attenuated the increase in RSND and BP in HF rats compared with control rats. Alternatively, microinjection of the GABA agonist muscimol produced a dose-dependent decrease in RSND, BP, and HR in both control and HF rats. Muscimol was also less effective in decreasing RSND, BP, and HR in HF rats than in control rats. These results suggest that endogenous GABA-mediated input into the PVN of rats with HF is less effective in suppressing RSND and BP compared with control rats. This is partly due to the post-release actions of GABA, possibly caused by altered function of post-synaptic GABA receptors in the PVN of rats with HF. Reduced GABA-mediated inhibition in the PVN may contribute to increased sympathetic outflow, which is commonly observed during HF.
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Affiliation(s)
- Kun Zhang
- Department of Physiology and Biophysics, University of Nebraska Medical Center, Omaha, Nebraska 68198-4575, USA
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Zhang K, Li YF, Patel KP. Blunted nitric oxide-mediated inhibition of renal nerve discharge within PVN of rats with heart failure. Am J Physiol Heart Circ Physiol 2001; 281:H995-1004. [PMID: 11514264 DOI: 10.1152/ajpheart.2001.281.3.h995] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have demonstrated a decreased neuronal nitric oxide (NO) synthase (nNOS) message in the hypothalamus of rats with heart failure (HF). Subsequently, we have demonstrated that NADPH diaphorase (a commonly used marker for nNOS activity) positive neurons are decreased in paraventricular nucleus (PVN) of rats with coronary artery ligation model of HF. The goal of the present study was to examine the influence of endogenous NO within the PVN on renal sympathetic nerve discharge (RSND) during HF. In alpha-chloralose- and urethane-anesthetized rats, an inhibitor of NO synthase, N(G)-monomethyl-L-arginine (L-NMMA) microinjected into the PVN (50, 100, and 200 pmol in 50-200 nl) produced a dose-dependent increase in RSND, blood pressure, and heart rate in control and HF rats. These responses were attenuated in rats with HF compared with control rats. On the other hand, the NO agonist, sodium nitroprusside, microinjected in PVN produced a dose-dependent decrease in RSND and blood pressure in control and HF rats. These responses were less in rats with HF compared with control rats. These data suggest that the endogenous NO-mediated effect within the PVN of HF rats is less potent in suppressing RSND compared with control rats. These data support the conclusion that the NO system within the PVN involved in controlling autonomic outflow is altered during HF and may contribute to the elevated levels of renal sympathoexcitation commonly observed in HF.
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Affiliation(s)
- K Zhang
- Department of Physiology and Biophysics, University of Nebraska Medical Center, Omaha, Nebraska 68198-4575, USA
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